Video can be found here:

Most up-to-date STL and Editable Fusion 360 source files can be found here: https://bbprojects.technology/collections/stl-fusion-360-source-files/products/3d-printable-high-torque-strain-wave-gearbox-harmonic-drive

More info, schematics, parts list, etc... can be found here:
https://hackaday.io/project/187309-3d-printable-strain-wave-gearbox-harmonic-drive

I was fascinated by this type of gearbox and always wanted to make one. This type of gearbox is one of the most used in industrial robots. This type of gearbox only has a single reduction (in this case 2 because of the belt reduction) with a very high reduction ratio. Because of the single stage reduction there's almost no tolerance/play between input and output shaft. Conventional gearboxes use more gears to achieve the same reduction ratio, the tolerances between the gears add up resulting in greater tolerances/play between the input and output shaft.

Here are some specifications of the gearbox:
Max tested torque at 12V: 41.3kgcm or 4Nm
Total reduction ratio = 54:1

Big thank you to PCBWay for sponsoring this project. Due a price drop in raw materials, PCBWay can now provide PCB's at a reduced price. Use my referral link to get a 5$ discount when you sing up as a new user: https://www.pcbway.com/setinvite.aspx?inviteid=586251

Tools and materials I'm using can be found here: https://bbprojects.technology/pages/tools-and-materials

Feel free to take a look at my other designs:

Delta belt 3D-printer for automated series production: https://www.thingiverse.com/thing:5387221
Turning 50 cent into a Bitcoin: https://www.thingiverse.com/thing:4705186
3D printable antweight battlebot: Bulldog: https://www.thingiverse.com/thing:4623536
SpaceX inspired edf rocket: https://www.thingiverse.com/thing:4606751
3D printed high torque servo/gearbox version 2: https://www.thingiverse.com/thing:4547703
UMC - Universal motion controller: https://www.thingiverse.com/thing:4245315
3D-printable Davinci catapult gift card: https://www.thingiverse.com/thing:4067668
Arduino controlled photogrammetry 3D-scanner: https://www.thingiverse.com/thing:3958326
Fully 3D-printable turntable: https://www.thingiverse.com/thing:3723618
RC FPV tank rover: https://www.thingiverse.com/thing:3587738
Fully 3D-printable wind-up car gift card: https://bbprojects.technology/collections/stl-fusion-360-source-files/products/fully-3d-printable-wind-up-car-gift-card-files
3D-printable High torque servo/gear reduction: https://www.thingiverse.com/thing:3292860
'BOOM box' high voltage capacitor bank case: https://www.thingiverse.com/thing:2980012
Subby the interactive youtube subscriber robot: https://www.thingiverse.com/thing:2928254
robot hand || bionic hand prosthesis prototype: https://www.thingiverse.com/thing:2838239
3D-printable linear actuator: https://www.thingiverse.com/thing:2783959
Mini 3D-printable crossbow: https://www.thingiverse.com/thing:2710472
8 legged spider robot: https://www.thingiverse.com/thing:2470882
best 3D-printable bearing: https://www.thingiverse.com/thing:2349065

Have a nice day!